As the number of cellphone users has increased, so has concern over the potential health effects related to the release of microwave radiation emitted by the phones. Though studies have not shown a consistent link between cellphone use and cancer of the brain, nerves and other tissues of the head or neck, the market for protective devices is growing.

The claim: The Bodywell chip is a tiny black device that promises to reduce the unknown risks of non-ionizing cellphone radiation. The company claims you simply stick the $30 chip to the surface or battery case of a mobile device, and it will help balance the body's electromagnetic fields.

There's no scientific evidence suggesting shields reduce emissions. Moreover, devices that block only the earpiece or another small part of the phone are worthless because the entire phone can transmit electromagnetic waves, according to the Federal Trade Commission.

Devices may also interfere with reception; this forces the phone to boost its power to compensate, leading to an increase in radio frequency absorption.

The Bodywell chip doesn't claim to be a shield, according to Haim Einhorn, CEO of EZ Technologies, which owns Bodywell USA. Instead, it uses the natural frequencies associated with matter. When chips were "imprinted" with four specific frequencies, researchers measured a significant reduction in energy absorption by simulated brain cells when exposed to a radio frequency electromagnetic field (RF-EMF), said biomedical physicist Nachaat Mazeh, a research associate at Beaumont Health Systems in Royal Oak, Mich., and a consultant to Bodywell.

Mazeh agrees that non-ionizing radiation has not been shown to break the DNA of cells, which can potentially cause cancer. "But that doesn't mean it's not doing other damage," he said, referring to a 2009 review of 101 studies published in the journal Pathophysiology which found more than half reported a genotoxic effect. "The brain cell's functions could be affected when exposed to RF electromagnetic fields."

Still, the lack of published research on the Bodywell device and the Web site claims make some outside experts skeptical. For example, Bodywell says the chips have been "imprinted with frequencies that support the body's cells in the opposite direction of the phone's radiation emission, rendering the potentially harmful waves neutral."

Researcher James Lin, an expert on the biological interactions of electromagnetic radiation, said it's unlikely the device would protect a cellphone user from microwave radiation and called the claims "incomprehensible" and "technically meaningless."

"Frequencies are not imprinted in precise quantities. … There isn't such a thing," said Lin, a professor of bioengineering and electrical engineering at the University of Illinois at Chicago. "Frequencies must be generated not imprinted."

Decrease your exposure

The Food and Drug Administration has not cleared or approved products to shield exposure to radio frequency energy emissions from cellphones. This is because the agency doesn't find any risk associated with exposure. Radio frequency energy can be absorbed by tissues closest to where the phone is held, however, and if that makes you feel queasy, try to limit your exposure. The Federal Trade Commission suggests you do that by:

Use an earpiece or speakerphone.

Text more. Keep voice calls short.

Wait for a good signal. The phone works harder when the signal is weak, emitting more radiation.

CHICAGO/WASHINGTON (Reuters) - The head of the Federal Communications Commission is asking for a review of the agency's stance on radiofrequency energy emitted from cell phones amid lingering concerns that the devices may cause brain tumors.

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